Long Series Type S231T - Metric Bright finish. Flute type: 30 helix. Manufactured to BS 122: Part 4: 1980. Metric Tolerances Diameter: ~ up to 3.00. Tolerance: +0.013 -0.033 Diameter: Over 3.00 ~ up to 6.00. Tolerance:+ 0.020 -0.038 Diamete…View more